KR101145654B1 - Gas metal buried arc welding of lap-penetration joints - Google Patents

Abstract

A method of welding continuous or intermittent lap-penetration joints uses a gas metal buried arc (GMBA) welding process. A first component (22) is GMBA welded to an underlying second metal component (24), by forming an arc (28) between a consumable metal electrode (26) and a surface of the first component (22), depositing metal from the electrode (26) to the first component (22) and producing a pool of molten metal (10) which extends through the first component (22) and into the second component (24). The molten pool metal solidifies into a weld (30) that extends into the second component (24) wherein the weld width at the interface between the components is at least equal to the thickness of the thinner of the first component (22) and the second component (24). The arc (28) is at least partially buried within the thickness of the first component and is moved in the direction of the desired joint location to produce a joint.

Description

GAS METAL BURIED ARC WELDING OF LAP-PENETRATION JOINTS}

The present invention relates to welding of overlap penetration joints, and more particularly to gas metal buried arc welding of overlap penetration junctions.

Gas metal arc welding of metal components (members) requires applying a current to the consumable metal electrode of the torch and forming an arc between the tip of the electrode and the surface of the component. The metal of the electrode is deposited on the component as a penetration material and forms a molten pool of metal comprising the electrode and the metal mixture of the component. A weld joint is formed upon solidification of the molten metal. Gasmetal arc welding is commonly used to join relatively thin (1 mm-4.5 mm) components such as overlap fillets, tea fillets and square butt joints. 1 schematically shows a gas metal arc welding of a square butt joint between two components 2, 4 with an arc made from the metal electrode 8. A molten metal pool 10 is formed between the electrode 8 and the components 2, 4 to produce a weld bead 12 that solidifies after passing the arc 6 and the weld zone of the molten pool 10. . Such bonds (overlap fillet bonds, tee fillet bonds and square butt bonds) require the tip 14 of the electrode to be positioned laterally within ± 0.5 mm of the weld edge where the arc is welded. Although control is provided during the welding operation through the use of robots and fixtures, various techniques have been used to ensure that the lateral position of the electrode arc is accurate relative to the joint.

One solution is to use precisely dimensioned components and welding fixtures, which adds significant cost to the final cost of the welding process. Alternatively or additionally to compensate for variations in dimensional tolerances of members, welding fixtures, and / or positioning devices, as well as changes in edge or edge position due to changes in the lateral position of the electrode tip and arc relative to the junction. Is oscillated with respect to the junction edge. Although vibrating the torch overcomes significant changes at the joining edges, the main disadvantage is that the productivity of the welding is significantly reduced, that is, the welding movement speed is reduced to allow vibrations to occur. Other methods for improving the junction / electrode relationship use images based on junction tracking systems, many of which are expensive, less reliable and difficult to maintain for aluminum components. Tactile junction tracking systems are effective, but have limited applicability in welding three-dimensional assemblies, such as to accommodate sharp edge or direction changes or to create multiple short joints.

In addition, since the weld (of the molten metal pool 10) does not reach the laminated component to a sufficient depth and the lower component and the weld do not fuse at the time of solidification, that is, they do not penetrate into the lower component. The method is known that overlap penetration bonding is not suitable for gas metal arc welding. In addition, spot welding of overlapping penetration joints with gas metal arc welding is known, but this is limited to those for structurally insignificant joints for some reasons. The combination of short welding time, insufficient current density applied during spot welding, and those that cannot catalyze surface oxides present on the joint surface between overlapping portions are limited within insufficient interfacial weld width and underlying components. A wine cup-shaped profile with weld penetration depth is shown. This results in relatively weak gas metal arc welded spot welds and limits their durability under fatigue loading.

Deeper gas metal arc welding, referred to as gas metal buried arc (GMBA) welding, has been achieved for square butt joints as shown in FIG. 2. The gas metal buried arc welding method is different from the conventional gas metal arc welding in that the welding current passing through the welding electrode is much higher in the gas metal buried arc welding method than the conventional gas metal arc welding method. This results in a higher current density in the gas metal buried arc welding method, which leads to a more penetrating aiming arc penetrating deeper into the component. However, so far deep gas metal buried arc welding of overlapping penetration bonding has not been achieved.

The present invention forms an arc between the consumable metal electrode and the surface of the first component, depositing metal from the electrode to the first component and forming a pool of molten metal extending through the first component and into the second component. Overlapping penetration joining consisting of gas-metal arc welding to a second metal component underlying the first metal component. When the molten metal pool solidifies into the weld, the width of the weld at the interface between the two components is at least equal to the thickness of the thinner of the first and second components. During welding, the arc is at least partially embedded into the thickness of the first component and moved in the direction of the desired joint position to create a joint.

1 is a schematic diagram of a prior art for gas metal arc welding of a square butt joint;

2 is a schematic diagram of a prior art for gas metal buried arc welding of a square butt joint;

3 is a side view of a weld of overlap penetration joint according to the method of the present invention;

Figure 4 is a side view of the junction made in Figure 3,

5 is a graph of the proposed match of electrode supply speed, welding current and moving speed for practicing the present invention.

The terms "top", "bottom", "left", "right", "vertical", "horizontal", "up", and "down" for the following description mean directions in the drawings in connection with the present invention. It is. However, the present invention may assume various modifications and steps of the present invention in addition to those explicitly shown. In addition, the specific apparatus and processes shown in the accompanying drawings and described below are exemplary embodiments of the present invention. Therefore, certain dimensions and other physical characteristics of the embodiments described herein should not be considered as limiting.

The present invention includes a gas metal buried arc welding method of overlap penetration bonding. In order to overcome the above-mentioned problems of gas-metal arc welding of overlap penetration junctions (ie, it is not possible to remove surface oxides from the junction surface in a negative manner, limited penetration and insufficient interfacial depth), overlap penetration junctions are a high power density process. (E.g., laser beam, electron beam or plasma welding). Referring to FIG. 3, the first metal component 22 is positioned in contact with the second metal component 24. The first and second components 22, 24 may be located in a vertical stack or in other arrangements as shown. High current (e.g., conventional gas metal arc welding) to a welding torch with metal consumable 350 amps compared to 150 amps). The metal of electrode 26 also melts with components 22 and 24 to form melt pool 10, which solidifies to become weld bead 30. The arc 28 penetrates and dissolves through the top of the first component 22 and the second component 24 to form a weld 30 between the two components 22, 24. The high current density maintained by the arc 28 provides sufficient electromagnetic force and heat to break through and dissolve through the oxide layer present at the bonding surface between the components 22, 24, through the stacked components It has a number of effects, including infiltration and vigorous stirring of the melt pool. In this way, the gas metal buried arc welding of the overlap penetration junction compensates for the absence of cathodic arc cleaning of the interfacial oxide by floating the oxide over the weld in the form of fracture, dissolution and slag while simultaneously providing the desired weld geometry (i.e. penetration and Interface depth).

Referring to FIG. 4, a weld 30 is made under process conditions that ensure that the width and depth of the weld 30 is sufficient to successfully create an overlapping penetration bond. For this purpose, the penetration depth D of the weld that penetrates into the second component 24 should be sufficient to dissolve the second component 24 and fuse and / or coalesce with the weld upon solidification. For a relatively thin component (1-5 mm), 5-10% penetration into the second component 24 is appropriate. In addition, the weld width W of the interface between the first and second components 22, 24 should be at least as large as the thickness T or t of the thin component among the respective components 22, 24. do. In FIG. 4, component 24 is shown as a thicker component, meaning that components 22 and 24 are limited to the same thickness or that component 22 is thinner than component 24. no. The electrode and arc are moved in the direction of the desired bonding position between the first and second components 22, 24. Welding may be performed continuously or intermittently to create a stitch weld.

Suitable materials for overlap penetration welding according to the present invention are components of aluminum alloys of the Aluminum Association (AA) using AA alloys as electrodes. The two components can be plate, cast or extruded material and combinations thereof. By way of example, the present invention welds two AA 5754-O plates of 2 mm thickness together using AA 5356 electrode at 300 amperes, and two AA 7075-T6 plates of 2 mm thickness AA 6062-T4 to 4 mm thickness. Successfully bonding to the extrudate was performed. The gas metal buried arc welding of the present invention is also suitable for creating overlapping penetration joints between components made of other materials such as steel, stainless steel, titanium and titanium alloys, copper and copper alloys.

Overlap joints made in accordance with the present invention are gas metals of other joints, such as overlap fillet joints that require slower welding movement speeds and / or torch vibrations to accommodate lateral changes in electrode tip / arc position relative to the joint edge. It can be made with higher efficiency than arc welding. Typical travel speeds for gas metal arc welding of overlap fillet joints are about 0.6 to 1.2 meters / minute for welding 2.5 mm thick components, but for metals of the same thickness the gas metal buried of the overlap penetration joints according to the invention. The movement speed of arc welding is about 1.5 to 2 meters / minute. In addition, the present invention can avoid the need for strict dimensional tolerances for the components because the lateral position of the electrode tip / arc relative to the component edge in the overlap penetration junction is less important than for other joints. And simplify assembly procedures (ie, fixing and welding procedures). Another advantage of gas-metal buried arc welding of overlap penetration welding is that it maximizes the use of the welding system and does not require expensive welding systems conventionally used for overlap penetration welding of laser beams, electron beams and plasma welding. The equipment can be used for both gas metal buried arc welding and gas metal arc welding. This can be achieved through switching between the two welding modes when making different joints (ie, overlap penetration welding and overlap fillet welding, tee fillet welding, etc.) in the same or different assemblies. In addition, the faster travel speed in gas metal buried arc welding of overlap penetration joints reduces the overall distortion due to welding that occurs during gas metal arc welding of overlap fillet joints between components of corresponding thickness.

Depending on the application, the gas metal buried arc welded overlap penetration junction can be fabricated using DC current as either a positive polarity electrode or a negative polarity electrode. The invention may also be practiced with other pulsed and non-pulsed (eg, square wave, AC) current and / or wire supply conditioning systems. In order to achieve controlled welding start and stop (ie, consistent normal quality and geometrical properties) during gas metal buried arc welding of overlap penetration joints, a welding system capable of programming a welding start and end procedure can be used. As shown in FIG. 5, the electrode feed rate (or wire feed rate (WFR)) matches the welding current and can be programmed to increase and decrease as a function of different thicknesses and alloy combinations. In some examples, weld initiation and termination procedures may be programmed to match the electrode feed rate / welding current and weld movement speed.

While the preferred embodiment has been described, the invention can be practiced in other ways within the scope of the appended claims.

Claims (9)

1. A method of gas metal buried arc welding of an overlap penetration bond between a first metal component and a second metal component underlying the first metal component. Forming an arc between the consumable metal electrode and the first component; Depositing a metal from the electrode to the first component and creating a pool of molten metal extending through the first component and into the second component underlying the second component; Solidifying the molten metal pool into the weld; And Moving the arc and the electrode across the surface of the first component to create a junction; A method of gas-filled arc welding of overlap penetration bonding, characterized in that the width of the weld at the interface between the first component and the second component is greater than or equal to the thickness of the thinner of the first component and the second component. . 2. A method according to claim 1, wherein the weld penetrates into the second component and fuses with the second component upon solidification. The method of claim 1, wherein the arc is located at least partially within the thickness of the first component. The method of claim 1, wherein the first and second components are aluminum alloys. The method of claim 1, wherein the first and second components are made of a material selected from the group consisting of steel, stainless steel, titanium and titanium alloys, copper and copper alloys. . 5. A method as claimed in claim 4, wherein the first component and the second component are each selected from the group consisting of plate, cast, extruded or forged material. The method of claim 1, wherein the arc and the electrode are moved at a speed of at least 1 meter per minute. The gas metal buried arc welding method according to claim 1, wherein the welding is performed continuously. The gas-metal buried arc welding method according to claim 1, wherein the welding is performed intermittently.

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